ABSTRACT Agitation and aggression are common in older adults with dementia. To date, there is no FDA-approved treatment strategy available for managing these symptoms. Furthermore, treatments that are used off-label (i.e., antipsychotics) in this clinical context have significant risks associated with them. Preliminary reports suggest that electroconvulsive therapy (ECT) may be efficacious as a treatment in this context. A number of small, within-group comparison studies have reported a general improvement in agitation, aggression, and level of functioning following ECT in patients with dementia. However, several limitations limit the certainty of these conclusions, including the small sample size and lack of a control group in the studies. Furthermore, these reports do not have long-term follow-up beyond the initial index series of ECT (only 3-5 weeks). The proposed supplement study will fill these gaps in knowledge by conducting a propensity-score matched observational cohort of respectable sample size (N~1000 per group) and duration (1-2 years) using nationally representative Medicare claims data. This application is in response to NOT-AG-20-008, which calls for supplemental projects to ?expand existing awards not currently focused on Alzheimer?s disease and its related dementias (AD/ADRD)? which will lead to subsequent independent research projects. This project will aim to 1) examine the association of ECT use with long-term disruptive behavioral symptoms (e.g., aggression and agitation); and 2) evaluate the association of ECT use with long-term cognitive and physical functional outcomes among older adults with co-morbid depression and dementia. We will compare outcomes over time across those who receive ECT and those who do not (non-ECT group). The outcomes of interest come from the OASIS survey, a comprehensive quarterly assessment of dementia patients in nursing homes. This survey contains detailed data on behavioral, cognitive, and functional outcomes. Data will be drawn from Medicare data of 650,000 beneficiaries aged 65 or older that is already in- house for the parent grant. Given this existing database, our preliminary data queries suggest we will have sufficient data for a longitudinal study of 2,000 patients. We will use a propensity-score matched cohort to identify a group of patients who do not receive ECT who are otherwise comparable to those who do. A mixed- model analysis will be utilized to examine outcomes over time. Our hypothesis is that ECT is associated with better outcomes compared to the non-ECT group. Our focus on comorbid depression/dementia is out of convenience given the dataset that exists in-house and the limitations of the supplement notice that the work must be completed in one year. Promising findings from this study would provide preliminary data to undertake a larger, independent study of this association in a more representative sample of individuals with dementia without depression, making anticipated findings more generalizable and relevant to practice.